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AP Chemistry
5.3 Concentration Changes Over Time
5.1 Reaction Rates
IntermediateMCQGraphicalConceptual17.5k
A grayscale Cartesian coordinate graph showing a single smooth, solid curve representing reactant concentration over time. The horizontal axis is labeled 'Time (s)' with tick marks at 0, 100, 200, and 300. The vertical axis is labeled '[H2O2] (M)' with tick marks at 0.00, 0.25, 0.50, 0.75, and 1.00. The solid curve starts at the coordinate (0, 1.00) and decreases monotonically with a decreasing slope (concave upward), passing through (100, 0.50) and (200, 0.25), approaching 0 at longer times. No other curves, data points, or annotations appear.
Concentration of \(\text{H}_2\text{O}_2\text{(aq)}\) as a function of reaction time.
A student investigates the kinetics of the first-order decomposition of hydrogen peroxide at a constant temperature of \(298\text{ K}\):

\[ 2\text{H}_2\text{O}_2\text{(aq)} \rightarrow 2\text{H}_2\text{O(l)} + \text{O}_2\text{(g)} \]

The concentration of \(\text{H}_2\text{O}_2\text{(aq)}\) is monitored over time, producing the curve shown in the graph. The student identifies the following four reaction rate values:

\(r_0\): the instantaneous rate of decomposition at \(t = 0\text{ s}\)
\(r_1\): the instantaneous rate of decomposition at \(t = 100\text{ s}\)
\(r_2\): the instantaneous rate of decomposition at \(t = 200\text{ s}\)
\(r_{\text{avg}}\): the average rate of decomposition over the time interval from \(t = 0\text{ s}\) to \(t = 100\text{ s}\)

Which of the following correctly ranks these four rates from greatest to least?

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